Valve-gear for steam-eitgines



UNITED STAT ES 'PATENT OFFIOE.

GEO. B. MILNER, OF HOUSTON, TEXAS.

VALVE-GEAR FOR STEAM-ENGINES.

Specification of Letters Patent No. 7,529, dated July 30, 1850.

on the extremities of the rock shafts, and

connecting rod, on an enlarged scale. Fig.

4, is a side elevation of the chamber through` which the steam passes tothe cylinder, steam chests at the ends of the same, levers for raisingthe valves &c., on an enlarged;

. two wrists one above and the other below scale.

Similar letters in the gures refer to corvresponding parts.

The nature of this invention and improvement consists in attaching theend of the connecting rod which operates the valves for ad mitting steamto the cylinder, to the center of a transverse traversing bar or leverattached by bolts, at its extremities to parallel slid ingrods, one ofwhich operates the escape valves, and both being provided `with squareframesat their ends surrounding D, shaped cams or eccentrics secured onthe main shaft, one of which is made movable and provided with asegmental slot through which is passed a bolt so as to enable said camor eccentric to be secured in such relation to the other cam oreccentric as to cut the steam olf when the piston has reached anydesired point in its stroke, and to cause the steam admitted to thecylinder to expand and exert its force on the piston the re mainder ofits` stroke.

To enable others skilled in the art to make and use my invention I willproceed to describe its construction and operation.

vA, is an inclined frame consisting of two inclined parallel beamssupported by upright and inclined timbers made of suitable size,strength, andmaterial, to contain and support the several parts oft-heengine.

B, is the cylinder secured within this frame near its lower end in aninclined position provided with the usual piston rod (a), pitman rod(b), crank (c), secured to a horizontal shaft, turning in suitableboxes, at the proper elevation.

O, are steam chambers arranged on the sides of the cylinder B, andextending parallel to the same from one end to the other. Thesechambers, communicate at their ends, through steam chests and branchtrunks, with the ends of the cylinder, which steam chests are providedwith puppet valves, secured to the lower end of rodsattached at theirupper ends to lever (el), turning on bolts `at their ends passingthrough them and through ears, formed at the upper end of upright posts,resting on pieces projecting beyond the ends of the steam chamber.

D, is a transverse rock shaft oscillating in openings in suitableuprights secured to the steam chambers and having a crank (e), securedto one of its extremities and an arm (f), terminating in a handle aboveand provided at equal distances from the center with the rock shaft, tothe upper one of which is attached a connecting rod (g), having a bars,and supported by the rod (7L), and` by a short rod (j), secured to oneof the beams and passing through a box secured to the frame A, in whichit moves.

E, is a cam wheel secured on the crank shaft (0'), inside the squareframe (5). This cam is made in the form of a segment of a circle,scribed from the center of the crank shaft, on part of its edge, and theremainder of its edge is made in the form of a semi parabola, so as tosomewhat resemble in its side elevation the letter D.

F, F, are horizontal transverse rock shafts, arranged on a line witheach other over the cylinder and steam chambers, and turning in openingsin upright posts erected on the steam chambers, and in an opening in apost rising from the top of the cylinder midway between its ends. Theserock shafts F, F, have cranks (lo, c), secured to their outer ends,similar to the crank (e) `notch near one of its ends, by which it is onthe rock shaft D, one of which cranks, (the one (72), on the shaft F,)is connected to the crank (e), by a connecting rod (Z )G5 G', are curvedtoes or lifters, projecting from the rock shafts F, F, immediately underthe ends of the levers (d), on the sides of the cylinder, foralternately lifting the ends of said levers and raising the valves inthe steam chests to admit and discharge the steam to and from thecylinder.

H, is a connecting rod, similar to t-he rod (g), except that it islonger, and connected to the crank (7c), on the rock shaft F, by meansof a notch in its end, in which the wrist of said crank ts, and arrangedoutside the rod This rod H, extends toward the main crank shaft parallelto the rod (g), and the same distance and is secured at its end to theend of a rod or shaft (m), passing through a box in one of theprojections on the side of the frame A, in

`which it slides, and connected by a pin to the center of a traversinglever or bar (n), attached by a pin at one of its ends to the slidingrod or shaft (it), and at its opposite end by a pin to a similar rod orshaft (o), passing through boxes in t-he projections on the side of theframe Yand jointed and attached at its end to a square frame (p), formedand supported in a similar manner to the frame I, is a cam wheel similarin size and form to the cam wheel E, and mounted on the main crank shaftwithin the square frame (p). 'This cam I, is bored to fit loosely over ahub (g), secured permanently on the crank shaft so as to enable it to beturned on said hub in order to bring its segmental and semi parabolicedges in any desired relation to the segmental and semi parabolic edgesof the cam E, for the purpose of regulating the cut off of the steamfrom the boiler, and contains a segmental slot y(1"), at its Widest partmidway between its rounded corners, scribed from the center of the crankshaft, and can be clamped against a circular rim (s), surrounding thecrank shaft against which it rests by means of a screw bollt passingthrough said rim and through the segmental slot (r), and through apointer or hand (w), secured by a pin to the hub (g), and extendingVtowagd the segmental edge of the camradial with the center of the crankshaft, and having a nut on its end by which said cam is forced againstt-he rim The mode of operation is as follows: The steam from the boilerbeing admitted to the chamber on one side of the cylinder, through thepipe The engineer raises one of ,the levers (d), situated over thechamber into which the steam is admitted, and allows lthe steam to` passthroughV the steam chest and 'trunk into the cylinder so as to D, andmove the rock shafts F', by the cranks (e, c), and connecting rod (l),so as to raise the end of the levers (CZ), and alternately open theescape valves to let off the steam from the cylinder about the time thepiston has reached the terminus of its stroke.

Before introducing the steam to the cylinder in the manner beforestated, the engineer unclamps the cam I, and turns it on the hub (g), soas to bring the po-inter (w), opposite the desired number on the graduY, ated plate on its face indicating the points to set opposite thepointer (w), to cut off the steam, at any required point of the strokeof the piston, and clamps it by turning the nut. It. may be well toobserve here that when the pointer 0r hand (fw), is oposite the figure17 on the graduated plate or index the two cams will be exactly in thesame relation to the crank and in their revolutions with the same willbe caused to move the square frames and 20,), simultaneously and operatethe several valves so as to employ the full force of the steam the wholeextent of the stroke; and that when the cam I, is turned on the hub so.as to bring any of the succeeding numbers of the graduated plate orindex opposite the pointer or hand (fw), the steam will be cut olf afterthe piston has proceeded on its stroke to a'point corresponding with Ythe number on the graduated plate or index, at which the pointer or handis situated, and the distance between said number and number one. Thiseffect is produced in the following manner: Supposing the point-er to beopposite number 4 as represented in the drawing and the engine to be inoperation. The escape valves will be moved at the terminus of eachstroke by the cam E, moving the frame and its attachments. At the timethis movement takes place the segmental edge of the cam I, is next oneof the upright beams of the square frame (p), which for the present isheld stationary causing likewise the end of the lever or traversing bar(n), attached to the rod or shaft of said frame to be held stationary.When the rod or shaft (71,) is moved by the cam E, the connecting rod isalso caused to move by the lever, or traversing bar (n), causing one ofthe valves in the steam chests to be opened by the lifters G, raisingthe end of one of the levers (d), and the steam to be admitted to oneside of the piston at the instant the steam is allowed to discharge fromthe opposite side of said piston. The admission valve Will be keptraised so as to admit the full force of steam to the piston until therounded corner of the edge of the cam I, Where the segmental andparabolic parts join each other, which is situated some distance inadvance of the same corner of the cam E, ovving to the movement of thecam I, on the hub (g), strikes the upright of the frame (p), When theframe (p), will be moved, carrying With the pointed rod 0r shaft (o),and causing the connecting rod I-I, to be moved by the lever or'traversing bar (n), and the lifter G, to be lowered from under the lever(cl), and the valve attached to the same to be closed so as to cut oiicthe steam from the boiler and the steam Within the cylinder to expanditself until the piston reaches the terminus of its stroke When the camE, Will cause one of the escape valves to be opened and the otherclosed, and the valve attached to the other lever (cl), to be raised toadmit the steam to the opposite side of the piston, and at the samepoint of the return stroke of the piston the steam will be again cut oi'by the cam I. In this manner the steam can be out 0H at any point of thestroke, by simply moving the cam I, over the hub (g), and the engineeris enabled to make liis engine at all time exert a uniform power, byregu-A lating the point at Which the steam is cut off and commencesWorking expansively, according to the pressure of the steam employed.

Having thus fully described my improvement, what I claim as new anddesire to secure by Letters Patent is- The combination of the fixed camE, with its frame and rods, and the adjustable cam I, With its frame androds, to Which latter are attached the traversing and oscillating bar a,having secured to one end of the rod g, and at or near its center therod H, which actuate respectively the eduction and induction valves,substantially in the manner herein described, forming together a simplevalve motion and one which enables .the engineer to regulate the degreeof cut off at Will.

GEORGE B. MILNER.

lVitnesses:

L. B. BRAGG, THos. MILNER, Jr.

